Parts of the Death Valley salt pan consist of these formations, which are a few inches high and composed of salt and hardened mud. They typically break underfoot, though not easily, and walking on them barefoot would probably be a painful, bloody experience. Driving over them wouldn't be too pretty, either.
One area where these formations are concentrated is called the Devil's Golf Course; it is a few miles north of Badwater basin. The formation shown here was near Mustard Canyon, close to the northern end of the salt pan.
Death Valley National Park, CA-- March 2008